Memory is not so much a faculty as it is a function of all the faculties. There is a memory in all the organs of the body. Memory is often restricted, for instance, to memory of words. But an idiot may excel here. There is also a memory for ideas, place, form, time, tune, etc. One remembers reasons better than anything else; another is deficient here. One has large memory of form, makes a mental picture of all that he sees. It is said of Cuvier that he never forgot the shape of any object he had once seen. Another man failed to recognize his brother and sister, and said he would not like to identify his wife in a court of law.
One man has a good memory for numbers, another has not. George Combe studied mathematics for seven years but could never master the multiplication table.
The cultivation of memory, therefore, is not simply the culture of one faculty, but the harmonious development of all the faculties.
A good memory is the characteristic of great men. Locke said a man who had a poor memory was stupid and dull. Ouintilian called memory the measure of genius. Milton's memory, like his poetry, rarely has been excelled. Bacon, of whom Macaulay said that "he probably had the most imperial mind of any man that lived," had a remarkable memory. Macaulay himself, who wrote for immortality, could repeat many books with ease.
Webster, Clay and Calhoun were as celebrated for their memories as their oratory. Sir Walter Scott, whose works changed the reading of humanity, could repeat long poems after hearing them read only once. Pascal, the saint and savant of France, knew the Bible by heart and could repeat any verse without hesitation.
Gibbon and Carlyle, both eminent historians, carried their library in their heads. Sir William Gladstone, the genius of the nineteenth century, is said to have torn the heart out of more books than any of his contemporaries. Cardinal Mezzofanti, Max Muller and Elihu Burritt had the languages of the world at their finger-ends. The list might be indefinitely continued. Dugald Stewart said he did not know a person eminently distinguished who did not have a good memory.
Retaining and recalling knowledge is not one and the same thing. Some who know cannot tell what they know. They are walking encyclopedias, but not talking encyclopedias. Some see and hear things but once and never forget.
It is not what we put into our mind, but how we put it there, that determines the ability to recall and use knowledge at will. An idea comes to the mind; whether it shall enter depends upon the state of the mind. If the mind is preoccupied the idea will vanish. If the mind is attentive the idea will enter, but it will not remain unless it associates itself with some other idea in the mind. When one of these ideas is recalled it will suggest the other. The facility or difficulty with which they can be recalled depends upon the vividness of first impressions.
The memory has a two-fold power, the power to retain ideas and the power to recall ideas.
Ideas are best fixed in the memory by Concentration, Association and Classification.
The faculty of recalling ideas is best established through Interest, Determination. Review, Meditation, and the culture of the Subjective Memory.